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  <title>用回调函数过滤数组中的单元</title>
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  <div id="layout-content"><div id="function.array-filter" class="refentry">
   <div class="refnamediv">
    <h1 class="refname">array_filter</h1>
    <p class="verinfo">(PHP 4 &gt;= 4.0.6, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">array_filter</span> &mdash; <span class="dc-title">
     用回调函数过滤数组中的单元
    </span></p>

   </div>
 <div class="refsect1 description" id="refsect1-function.array-filter-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="methodname"><strong>array_filter</strong></span>
    ( <span class="methodparam"><span class="type">array</span> <code class="parameter">$array</code></span>
   [, <span class="methodparam"><span class="type"><a href="language.types.callable.html" class="type callable">callable</a></span> <code class="parameter">$callback</code></span>
   [, <span class="methodparam"><span class="type">int</span> <code class="parameter">$flag</code><span class="initializer"> = 0</span></span>
  ]] ) : <span class="type">array</span></div>

    <p class="para rdfs-comment">
     依次将 <code class="parameter">array</code> 数组中的每个值传递到
     <code class="parameter">callback</code> 函数。如果
     <code class="parameter">callback</code> 函数返回 true，则
     <code class="parameter">array</code>
     数组的当前值会被包含在返回的结果数组中。数组的键名保留不变。
    </p>
   </div>


 <div class="refsect1 parameters" id="refsect1-function.array-filter-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>


    
     <dt>
<code class="parameter">array</code></dt>

     <dd>

      <p class="para">
       要循环的数组
      </p>
     </dd>

    

    
     <dt>
<code class="parameter">callback</code></dt>

     <dd>

      <p class="para">
       使用的回调函数
      </p>
      <p class="para">
        如果没有提供 <code class="parameter">callback</code>
     函数，
     将删除 <code class="parameter">array</code> 中所有等值为
     <strong><code>FALSE</code></strong> 的条目。更多信息见<a href="language.types.boolean.html#language.types.boolean.casting" class="link">转换为布尔值</a>。
      </p>
     </dd>

    

    
     <dt>
<code class="parameter">flag</code></dt>

     <dd>

      <p class="para">
       决定<code class="parameter">callback</code>接收的参数形式:
       <ul class="itemizedlist">
        <li class="listitem">
         <span class="simpara"><strong><code>ARRAY_FILTER_USE_KEY</code></strong> - <code class="parameter">callback</code>接受键名作为的唯一参数</span>
        </li>
        <li class="listitem">
         <span class="simpara"><strong><code>ARRAY_FILTER_USE_BOTH</code></strong> - <code class="parameter">callback</code>同时接受键名和键值</span>
        </li>
       </ul>
      </p>
     </dd>

    

   </dl>

  </p>
 </div>


 <div class="refsect1 returnvalues" id="refsect1-function.array-filter-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   返回过滤后的数组。
  </p>
 </div>



 <div class="refsect1 changelog" id="refsect1-function.array-filter-changelog">
  <h3 class="title">更新日志</h3>
  <table class="doctable informaltable">
   
    <thead>
     <tr>
      <th>版本</th>
      <th>说明</th>
     </tr>

    </thead>

    <tbody class="tbody">
     <tr>
      <td>5.6.0</td>
      <td>
       添加可选的参数 <code class="parameter">flag</code>，以及常量
       <strong><code>ARRAY_FILTER_USE_KEY</code></strong> 和 
       <strong><code>ARRAY_FILTER_USE_BOTH</code></strong>。
      </td>
     </tr>

    </tbody>
   
  </table>

 </div>

 


 <div class="refsect1 examples" id="refsect1-function.array-filter-examples">
  <h3 class="title">范例</h3>
  <p class="para">
   <div class="example" id="example-6027">
    <p><strong>Example #1 <span class="function"><strong>array_filter()</strong></span> 例子</strong></p>
    <div class="example-contents">
<div class="phpcode"><pre><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /></span><span style="color: #007700">function&nbsp;</span><span style="color: #0000BB">odd</span><span style="color: #007700">(</span><span style="color: #0000BB">$var</span><span style="color: #007700">)<br />{<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #FF8000">//&nbsp;returns&nbsp;whether&nbsp;the&nbsp;input&nbsp;integer&nbsp;is&nbsp;odd<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #007700">return(</span><span style="color: #0000BB">$var&nbsp;</span><span style="color: #007700">&amp;&nbsp;</span><span style="color: #0000BB">1</span><span style="color: #007700">);<br />}<br /><br />function&nbsp;</span><span style="color: #0000BB">even</span><span style="color: #007700">(</span><span style="color: #0000BB">$var</span><span style="color: #007700">)<br />{<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #FF8000">//&nbsp;returns&nbsp;whether&nbsp;the&nbsp;input&nbsp;integer&nbsp;is&nbsp;even<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #007700">return(!(</span><span style="color: #0000BB">$var&nbsp;</span><span style="color: #007700">&amp;&nbsp;</span><span style="color: #0000BB">1</span><span style="color: #007700">));<br />}<br /><br /></span><span style="color: #0000BB">$array1&nbsp;</span><span style="color: #007700">=&nbsp;array(</span><span style="color: #DD0000">"a"</span><span style="color: #007700">=&gt;</span><span style="color: #0000BB">1</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"b"</span><span style="color: #007700">=&gt;</span><span style="color: #0000BB">2</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"c"</span><span style="color: #007700">=&gt;</span><span style="color: #0000BB">3</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"d"</span><span style="color: #007700">=&gt;</span><span style="color: #0000BB">4</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"e"</span><span style="color: #007700">=&gt;</span><span style="color: #0000BB">5</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$array2&nbsp;</span><span style="color: #007700">=&nbsp;array(</span><span style="color: #0000BB">6</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">7</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">8</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">9</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">10</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">11</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">12</span><span style="color: #007700">);<br /><br />echo&nbsp;</span><span style="color: #DD0000">"Odd&nbsp;:\n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">array_filter</span><span style="color: #007700">(</span><span style="color: #0000BB">$array1</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"odd"</span><span style="color: #007700">));<br />echo&nbsp;</span><span style="color: #DD0000">"Even:\n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">array_filter</span><span style="color: #007700">(</span><span style="color: #0000BB">$array2</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">"even"</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</pre></div>
    </div>

    <div class="example-contents"><p>以上例程会输出：</p></div>
    <div class="example-contents screen">
<div class="cdata"><pre>
Odd :
Array
(
    [a] =&gt; 1
    [c] =&gt; 3
    [e] =&gt; 5
)
Even:
Array
(
    [0] =&gt; 6
    [2] =&gt; 8
    [4] =&gt; 10
    [6] =&gt; 12
)
</pre></div>
    </div>
   </div>
   <div class="example" id="example-6028">
    <p><strong>Example #2 不使用 <code class="parameter">callback</code> 时的<span class="function"><strong>array_filter()</strong></span>
    </strong></p>
    <div class="example-contents">
<div class="phpcode"><pre><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /><br />$entry&nbsp;</span><span style="color: #007700">=&nbsp;array(<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">0&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">'foo'</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">1&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">false</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">2&nbsp;</span><span style="color: #007700">=&gt;&nbsp;-</span><span style="color: #0000BB">1</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">3&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">null</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">4&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">''<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">array_filter</span><span style="color: #007700">(</span><span style="color: #0000BB">$entry</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</pre></div>
    </div>

    <div class="example-contents"><p>以上例程会输出：</p></div>
    <div class="example-contents screen">
<div class="cdata"><pre>
Array
(
    [0] =&gt; foo
    [2] =&gt; -1
)
</pre></div>
    </div>
   </div>
   <div class="example" id="example-6029">
    <p><strong>Example #3 带 <code class="parameter">flag</code> 标记的 <span class="function"><strong>array_filter()</strong></span>
    </strong></p>
    <div class="example-contents">
<div class="phpcode"><pre><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /><br />$arr&nbsp;</span><span style="color: #007700">=&nbsp;[</span><span style="color: #DD0000">'a'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">1</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'b'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">2</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'c'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">3</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'d'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">4</span><span style="color: #007700">];<br /><br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">array_filter</span><span style="color: #007700">(</span><span style="color: #0000BB">$arr</span><span style="color: #007700">,&nbsp;function(</span><span style="color: #0000BB">$k</span><span style="color: #007700">)&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;return&nbsp;</span><span style="color: #0000BB">$k&nbsp;</span><span style="color: #007700">==&nbsp;</span><span style="color: #DD0000">'b'</span><span style="color: #007700">;<br />},&nbsp;</span><span style="color: #0000BB">ARRAY_FILTER_USE_KEY</span><span style="color: #007700">));<br /><br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">array_filter</span><span style="color: #007700">(</span><span style="color: #0000BB">$arr</span><span style="color: #007700">,&nbsp;function(</span><span style="color: #0000BB">$v</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$k</span><span style="color: #007700">)&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;return&nbsp;</span><span style="color: #0000BB">$k&nbsp;</span><span style="color: #007700">==&nbsp;</span><span style="color: #DD0000">'b'&nbsp;</span><span style="color: #007700">||&nbsp;</span><span style="color: #0000BB">$v&nbsp;</span><span style="color: #007700">==&nbsp;</span><span style="color: #0000BB">4</span><span style="color: #007700">;<br />},&nbsp;</span><span style="color: #0000BB">ARRAY_FILTER_USE_BOTH</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</pre></div>
    </div>

    <div class="example-contents"><p>以上例程会输出：</p></div>
    <div class="example-contents screen">
<div class="cdata"><pre>
array(1) {
  [&quot;b&quot;]=&gt;
  int(2)
}
array(2) {
  [&quot;b&quot;]=&gt;
  int(2)
  [&quot;d&quot;]=&gt;
  int(4)
}
</pre></div>
    </div>
   </div>
  </p>
 </div>


 <div class="refsect1 notes" id="refsect1-function.array-filter-notes">
  <h3 class="title">注释</h3>
  <div class="caution"><strong class="caution">Caution</strong>
   <p class="para">
     用户不应在回调函数中修改数组本身。例如增加／删除单元或者对
     <span class="function"><strong>array_filter()</strong></span> 正在作用的数组进行
     unset。如果数组改变了，此函数的行为将不可预测。
   </p>
  </div>
 </div>

 
 <div class="refsect1 seealso" id="refsect1-function.array-filter-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="function"><a href="array_map.html" class="function" rel="rdfs-seeAlso">array_map()</a> - 为数组的每个元素应用回调函数</span></li>
    <li class="member"><span class="function"><a href="array_reduce.html" class="function" rel="rdfs-seeAlso">array_reduce()</a> - 用回调函数迭代地将数组简化为单一的值</span></li>
    <li class="member"><span class="function"><a href="array_walk.html" class="function" rel="rdfs-seeAlso">array_walk()</a> - 使用用户自定义函数对数组中的每个元素做回调处理</span></li>
   </ul>
  </p>
 </div>

  </div></div></div></body></html>